AuthorTopic: Neumann reissues the U67 (Read 19933 times)

Of course we're all looking for Klaus's review! But have been using it for months now & it's really a great mic, to say the least & in it's own right. Is it exactly & a replica of V.1 (or 2)? We'll wait for Klaus on that aspect of it.

Klaus,You stated: " ... a brand-new K870 (build date late 2012), and my jaw dropped: Both sides of the capsule are lush ... and are extraordinarily musical. Only the very best K67 from the mid 1960s (the famous 'fibre board' model) could hold a candle to this one ... I am hoping and praying that this is a trend, and will report what the next new K870 capsule portends."

I guess that the hope of it becoming a trend didn't live up - after reading your review of the U67 Reissue?

Very interesting review! So again, the tensioning of the capsule membranes is the biggest problem.Could you unveil a little how it is possible to relax the tensioning of the membranes?(Not that I am even thinking about doing this myself!!!)As far as I remember, the membranes were glued to the tensioning rings.(Anyway, that is what I saw when I took a damaged Neumann U87 capsule apart.)

Interesting. I remember I once removed the 'good' membrane from a damaged U87 capsule and used it to repair another U87 capsule. In this case, the membrane was definitely glued to the tensioning ring. (Otherwise I would never have been able to reuse it again!) The repaired microphone sounded good after this 'transplantation'.Anyway: the owner of the microphone was very happy with the result.Although the capsule looked as an original Neumann one, there is of course a chance that it had been replaced with a third party one. Or could it be that after many years of use the membrane just sticks to the tensioning ring? (I would be surprised if this happens.)

It is quite easy to unscrew the two halves of a k87/k870 capsule but if you touch even a single screw that is holding the diaphragm in place, you will ruin the tension in the diaphram.

Source: I took apart a diaphragm that had been ruined by an amateur cleaning attempt.

I can say with a certain authority that these diaphragms are both tougher and more fragile than most people realise. I imagine it is a thing of working with them a lot that helps you to understand in which ways they are tough and in which ways they are fragile.

I experimented on two completely ruined diaphragms... Had I experimented on a two working diaphragms, I would have ended up with two non-working diaphragms...

Interesting. I remember I once removed the 'good' membrane from a damaged U87 capsule and used it to repair another U87 capsule. In this case, the membrane was definitely glued to the tensioning ring. (Otherwise I would never have been able to reuse it again!) The repaired microphone sounded good after this 'transplantation'.Anyway: the owner of the microphone was very happy with the result.Although the capsule looked as an original Neumann one, there is of course a chance that it had been replaced with a third party one. Or could it be that after many years of use the membrane just sticks to the tensioning ring? (I would be surprised if this happens.)

Yes, I have seen many capsules that were destroyed by people who had attempted to 'clean' the membranes!Gold wiped off, holes in the membranes etc.Once I got a capsule that was cleaned so thorougly, that all the gold was gone...The owner asked if I didn't have a spraycan, so I could apply a new layer of gold. I explained to him that it didn't work this way...

Very interesting review! So again, the tensioning of the capsule membranes is the biggest problem.Could you unveil a little how it is possible to relax the tensioning of the membranes?(Not that I am even thinking about doing this myself!!!)As far as I remember, the membranes were glued to the tensioning rings.(Anyway, that is what I saw when I took a damaged Neumann U87 capsule apart.)

Heat could possibly decrease Mylar tension, but the problem in this case that is that it has gold bonded to it.

Any sort of pre-age/stress like heat would be best done before application of the gold, because with heating after the fact the gold and Mylar will not respond in the same way to heat, which may theoretically cause abberations in the bond, at least according to research.

That said, it’s hard to think of other approaches to tweak the tension of an assembled capsule.

When you have a drum head under tension and heat it, a dimple stretches and the Mylar thins. You can then tighten the drum head up more, heat again. Rinse and repeat. Until the drum head gets so thin that it’s shot or breaks.

I thought the pitch relaxed when it thins out on the head, with it being under tension. But it goes up more like shrink wrap? Interesting. I have some timbale heads here that I’ll do that to soon, and pay close attention.

Mylar is pre-tensioned or stetched during manufacturing. Depending on the tension used in the capsule it's more likely that heat will increase the tensioning.But - we do not know how Neumann treats the mylar in the manufacturing process.

Mylar is pre-tensioned or stetched during manufacturing. Depending on the tension used in the capsule it's more likely that heat will increase the tensioning.But - we do not know how Neumann treats the mylar in the manufacturing process.